Corrosion performance of reinforced mortar in the presence of polymeric nano-aggregates: electrochemical behavior, surface analysis, and properties of the steel/cement paste interface

Abstract

This study reports on the effect of admixed polyethylene oxide-b-polystyrene (PEO 113 -b-PS 70 ) micelles on corrosion behavior of reinforced mortar. The electrochemical measurement shows that the corrosion performance of the reinforcing steel was not significantly improved. However, surface analysis and microstructural investigation at the steel/cement paste interface reveal that the admixed micelles lead to a steel surface layer with enhanced barrier properties in terms of morphology and composition. Therefore, the presence of micelles further minimized and halted the corrosion process, despite the very aggressive, chloride-containing environment of 5% NaCl. The reasons and mechanisms behind the hereby observed corrosion behavior of reinforced mortar in the presence of micelles are related to the influence of these nano-aggregates on microstructural properties. These further results in altered water/ion transport and chloride-binding mechanisms in the bulk mortar matrix and thus steel product layer modifications towards enhanced corrosion resistance.

Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

“…1). The copolymer was synthesized by atom transfer radical polymerization (ATRP), employing the macroinitiator technique (Hu et al 2012b;Matyjaszewski and Xia 2001). The vesicles solution was prepared by dialysis: 0.5 g PEO 113 -PS780 diblock copolymer was dissolved in 800 ml 1,4-dioxane and 200 ml deionized water were added drop-wise.…”

“…In our previous research, the influence of polymeric micelles and vesicles (with a hydrodynamic radius of 50 nm and 220 nm) respectively on the corrosion performance of reinforced concrete was investigated (Hu et al 2012b(Hu et al , 2011(Hu et al , 2012c. Micelles are polymeric, self-assembled nano-architectures with amphiphilic properties in our case, whereas vesicles are nano-sacs, that enclose a volume, containing water or chosen substances.…”

“…Initial tests in simulated pore solution (Hu et al 2011) and reinforced mortar in the presence of micelles (Hu et al 2012b) proved that corrosion initiation was delayed on one hand and chloride binding capacity of the mortar was increased on the other. Further investigations on admixed vesicles, and especially Ca-containing ones, where saturated Ca(OH) 2 solution was pre-reserved in their core, (Hu et al 2012c) indicated "self-healing" effect of the corrosion damage in the reinforcement: after corrosion initiation, the steel corrosion resistance was significantly increased and corrosion propagation on the steel reinforcement was halted.…”

Self-healing of steel corrosion in a model alkaline medium: electrochemical response and surface analysis

“…Vesicles were prepared via dialysis from PEO 113 -b-PS 760 block-polymer [24][25][26][27][28]. In order to distinguish between "barrier" effects and "self-healing" due to Ca-release, both "empty" and Ca-containing vesicles were used.…”

“…For establishing the effects on corrosion resistance, the aforementioned micelles, as well as stabilized (kinetically frozen) PEO 113 -b-PS 760 vesicles (220 nm size), "empty" and Ca-containing ones, were studied [26][27][28]. The aim of these studies was to investigate the possibility for maintained positive effects on the cement-based microstructure, along with increased corrosion resistance and self-healing (or repair) of corrosion damage, resulting from Ca-core release.…”